The present invention relates to soy products, and more particularly to stabilized soy beverages manufactured from dehulled whole soybeans.
Soybean or legume based food products are known for their high protein content and other health benefits such as the reduction of blood cholesterol and incidents of osteoporosis. The manufacture of soy beverage products presents a variety of distinct problems due to the chemical composition of the soybeans. For example, typical whole soy beverages usually have a chalky or fibrous texture due to the complex carbohydrates present in the soybean cotyledons and hulls. Further, soy beverages are typically plagued with a xe2x80x9cbeanyxe2x80x9d flavor caused by enzyme activity, in particular, lipoxygenase activity, that results from the cell tissue of soybean cotyledons being disrupted in the presence of moisture and oxygen.
In conventional soy beverage manufacturing processes, these problems have been addressed. Typical soymilk beverages include a combination of water and soymilk concentrate produced from a process whereby whole soybeans are dehulled and blanched. To reduce the chalky texture of the soy beverage, the soybeans are dry-dehulled prior to processing. Dry-dehulling is the industrial process whereby the soybeans are heated so that the hull is separated from the cotyledon. The soybean hull is then physically cracked and subsequently separated from the cotyledon. Alternatively, the chalky texture may be reduced by extracting the soybeans. Conventional extraction includes crushing the whole soybeans in water and pressing the resultant slurry to squeeze out a soybean liquid. To address the xe2x80x9cbeanyxe2x80x9d flavor of the resultant soy beverage, the soybeans are blanchedxe2x80x94that is, boiled or steamed at very high temperatures. Blanching inactivates the lipoxygenase enzyme present in the soybean and eliminates the possibility of the soybean developing the xe2x80x9cbeanyxe2x80x9d flavor during subsequent processing. During the blanching step, however, the soy proteins are substantially denatured whereby solubilization of the soy proteins is inhibited.
Although manufacture of prior art soy beverages removes the chalky texture and xe2x80x9cbeanyxe2x80x9d flavor of the beverage, a distinct problem arises during storage of the beverage in containers. In particular, the beverage is extremely unstable. The beverage separates into at least two layers; a clumpy colloidal (particle) phase at the base of the container, and a free whey water phase at the top of the container. Accordingly, the beverage becomes unattractive in this separated, clumpy-looking state. Further, consumers must vigorously shake the container to recombine the colloidal phase and water phase before consuming the beverage to avoid an unpleasant texture. In the prior art, it was thought that the denaturation of the protein during the application of heat to inactivate the lipoxygenase was the cause of the colloidal separation.
To eliminate the unattractive appearance of prior art soy beverages, manufacturers conventionally package the beverage in opaque containers such as laminated paper boxes or colored plastic bottles. Although this conceals the separation of the colloidal phase and the water phase, the soy beverage still must be shaken to uniformly distribute the soybean particles in the water phase and prevent clumping when the beverage is poured from the storage container.
Manufacturers of soy beverages of the prior art have also addressed soy beverage instability by isolating soy nutraceuticals, such as particular soy proteins and soy isoflavones from whole soybeans, and putting the nutraceuticals alone in a beverage. Although the resultant soy beverage is somewhat stable, only a select few soy nutraceuticals are present therein. Thus, consumers obtain a limited number of soy nutraceuticals when they consume these soy beverages rather than the synergistic composition of all the soybean""s nutraceuticals.
The aforementioned problems are overcome in the present invention for manufacturing a stabilized soy beverage from dehulled-whole soybeans that are hydrolyzed with enzymes. The soy beverage produced from the inventive process exhibits stability for extended periods of storage, absence of a xe2x80x9cbeanyxe2x80x9d flavor and lack of a chalky texture. In particular, during storage, the colloidal and water phases of the soy beverage do not separate, even for extended periods of storage. Before consuming the soy beverage, agitation of the soy beverage is unnecessary, as the colloidal and water phases do not separate in storage. Further, the soy beverage of the present invention is created from dehulled-whole soybeans; therefore all of the beneficial nutraceuticals of the dehulled-whole soybeans, such as soy proteins, isoflavones, trypsin inhibitors, saponins, phytates, phosphatides, fiber, omega-3-fatty acids and vitamin E, to name a few, are present in the resultant beverage.
It has been discovered that colloidal separation of soy beverage during storage is caused by the binding of proteins and carbohydrates present in the whole soybeans used to manufacture the beverage. Once the proteins and carbohydrates bind together, the large macro molecules formed thereby tend to clump together and separate and/or precipitate out from the liquid phase. According to this discovery, the process of the present invention enzymatically hydrolyzes the soy proteins and soy carbohydrates to extensively inhibit binding to one another and subsequent colloidal separation. The resultant product of this process is a hydrolyzed soy base.
More particularly, the process of the present invention used to manufacture the hydrolyzed soy base includes the steps of: providing whole soybeans that include carbohydrates and proteins; hydrolyzing the proteins and hydrolyzing the carbohydrates so that the proteins and carbohydrates do not bind to form colloidal masses. In the preferred embodiment of the present invention, the process of manufacturing a hydrolyzed soy base includes the steps of: providing whole soybeans; soaking and preliminarily incubating the whole soybeans so that endogenous enzymes of the soybean are brought to a potentially active state; dehulling the soaked soybeans and separating the wet hulls from the cotyledons; incubating the cotyledons at a temperature so that enzymes present in the soybean begin to hydrolyze the soy protein and carbohydrates; gelatinizing the partially hydrolyzed complex polysaccharides in the incubated cotyledons by high temperature treatment; milling the boiled cotyledons into a slurry; adding enzyme(s) to the slurry to further enhance hydrolyzing the soy carbohydrates therein and then subsequently deactivating the enzyme; and, deodorizing the cotyledon slurry to form a hydrolyzed soybean base.
The process for formulating the hydrolyzed soybean base may be supplemented with additional steps to create a soy beverage. These additional steps include: mixing sweeteners, stabilization aids, and coloring of the hydrolyzed soybean base; homogenizing the resultant formulated mix; and either sterilizing the homogenized formulation at ultrahigh temperatures for batches to be stored at ambient temperature or pasteurizing the mix at lower temperatures for batches of the homogenized formulation to be refrigerated.
The hydrolyzed soy base manufactured from the process of the present invention has a wide variety of applications. For example, the soy base may be incorporated solely or in combination with dairy or a variety of other food products such as beverages, yogurts, deserts, infant foods, cream liquors, puddings, creams, spreads, cheeses, mayonnaise, sherbets, tofu, yuba, aburrage, milkshakes and soups.
These and other objects, advantages, and features of the invention will be more readily understood and appreciated by reference to the detailed description of the preferred embodiment and the drawings.
The present invention can be characterized as a method of manufacturing a soy base from dehulled-whole soybeans partially hydrolyzed with enzymes that may be combined with other ingredients to form a completed soy beverage. The soy base of this invention is an aqueous preparation of the soybean which exhibits: (a) stability of liquid soy base without separation of fat, sedimentation, or coagulation; (b) prolonged storage life; (c) absence of soy flavor; (d) maximum blending capability with fruit juices, fruit juice blends and/or natural or artificial flavors; (e) enhanced compatibility with coloring agents; and (f) increased palatability.
The soymilk of the present invention includes one or more of the following components, all of which are described in detail below: (a) a hydrolyzed soy base made from dehulled-whole soybeans; (b) water; (c) natural or artificial flavoring; (d) natural or artificial sweeteners; (e) stabilization aids; and (f) natural or artificial coloring.
The hydrolyzed soy base of the present invention is manufactured from whole soybeans. xe2x80x9cWhole soybeansxe2x80x9d are any known variety of soybeans with the hull intact. Whole soybeans include an exterior shell, or xe2x80x9chullxe2x80x9d that encapsulates the inner portion of the soybean, or the xe2x80x9ccotyledon.xe2x80x9d The xe2x80x9ccotyledonxe2x80x9d is the portion of the soybean used to produce the hydrolyzed soy base of the present invention. The cotyledon is comprised of a variety of different proteins including mono-, di-, and polypeptides, and sugars, including mono-, di-, and polysaccharides. The cotyledon also includes xe2x80x9cendogenous enzymes,xe2x80x9d which are those enzymes that metabolize proteins and sugars of the cotyledon to promote germination and growth of the soybean plant. Other components and chemicals present in the cotyledon include isoflavones, goitrogens, phytestrogens, Bowman-Birk trypsin inhibitors, saponins, phytates, phosphatides, fiber, fatty acids, vitamins, and minerals.
As will be appreciated by those skilled in the art, the endogenous enzymes include proteinases that, when activated, hydrolyze proteins of the soybean and carbohydrases that, when activated, hydrolyze the carbohydrates of the cotyledons. Another endogenous enzyme present in soybean cotyledons responsible for hydrolysis of fatty acids is the enzyme lipoxygenase which is also heat sensitive. The process for manufacturing the hydrolyzed soy base of the present invention is described in full detail below.
Water contributes to the solubility and stabilization of the hydrolyzed soy base and the completed soy beverage. The water content in the hydrolyzed soy base in one embodiment is at least about 65 percent, in a second embodiment from about 65 percent to about 95 percent, in a third embodiment from about 80 percent to about 90 percent. Parts and percentages are by weight unless otherwise mentioned and temperatures are in degrees Celsius unless otherwise specified.
Sweeteners and stabilization aids may be added to the hydrolyzed soybean base to form a complete soy beverage.
xe2x80x9cSweetenersxe2x80x9d include any chemical added to the soy beverage that enhances the sweet taste of the soy beverage. Exemplary sweeteners of a first embodiment of the invention are sucrose and fructose. Sucrose may be added in amounts from about 0% to about 10% in one embodiment, about 1% to about 6% in a second embodiment, and about 3% in a third embodiment. Fructose may be added in addition to or in place of sucrose. Fructose may be added to the soy beverage in amounts from about 0% to about 10% in a first embodiment, from about 1% to about 4% in a second embodiment, or about 2% in a third embodiment. Low calorie or reduced calorie sweeteners may be substituted for sucrose or fructose. Any artificial sweeteners such as aspartame, saccharin and its salts, acesulphame K and glycerrhizinic acid and salts, and their various combinations may also be substituted for or added to the natural sweeteners. The soy beverage can thus be formulated as a product sweetened with natural carbohydrate sweeteners and/or artificial sweeteners.
The flavor of the soy beverage may also be enhanced with flavoring. xe2x80x9cFlavoringxe2x80x9d refers to any natural or artificial flavoring, or combination thereof. The flavoring may include a variety of flavors including but not limited to strawberry, orange, berry, pineapple, or other fruity flavors. Other flavors such as chocolate, vanilla, etc. may also be used. To further enhance the flavor of the soy beverage, salts, for example, sea salt may be added. Sea salt may be added in amounts from about 0.0% to about 0.01% in a first embodiment, from about 0.0005% to about 0.005% in a second embodiment, and to about 0.001% in a third embodiment.
xe2x80x9cStabilization aidsxe2x80x9d refer to any substance that tends to keep the soy beverage solution from changing its form, color, or chemical composition. Stabilization aids keep any present pigments and other components in emulsion form and prevent the particles in a colloidal suspension from precipitating. One stabilizing aid is xanthan gum which may be used to keep the water and solids of the soy beverage together in a liquid phase. Xanthan gum may be present in the soy beverage from about 0% to about 0.01% in a first embodiment, from about 0.002% to about 0.008% in a second embodiment, and about 0.005% in a third embodiment. A second stabilization aid used in the soy beverage is lecithin or any derivatives thereof. The lecithin acts as an emulsifier for the oil present in the hydrolyzed soybean base. Lecithin may be present in the soy beverage from about 0.0% to about 0.1%, in another embodiment from about 0.005% to about 0.05%, and in another embodiment about 0.01%. Guar gum, a second suitable stabilization aid, may be present in a first embodiment from about 0.0% to about 0.01%; in a second embodiment from about 0.002% to about 0.008%, and in a third embodiment, about 0.005%. Carboxymethyl cellulose, yet another suitable stabilization aid, may be present in a first embodiment from about 0.0% to about 0.01%; in a second embodiment from about 0.002% to about 0.008%, and in a third embodiment, about 0.005%. As will be appreciated by those skilled in the art, other known stabilization aids may be used as desired.
There will now be described the inventive process used to manufacture the hydrolyzed soy base and completed soy beverage. To begin, whole soybeans are mixed and washed with water in a washing vessel.
The soybeans may be soaked in water having a temperature from about 15xc2x0 to about 45xc2x0 C. and a pH of about 6.0 to about 8.0 in a first embodiment, and at the same temperatures but at a pH of about 7.0 in a second embodiment. Depending on the temperature of the water, the time the soybeans are soaked may vary. When describing a temperature over a time period herein as xe2x80x9cconstant,xe2x80x9d it is meant that the temperature is maintained continuously at about the given temperature. When describing a temperature as an xe2x80x9cinletxe2x80x9d temperature, it is meant that the temperature of the liquid or other substance used is initially added with the specified temperature, however, the temperature may change with time due to cooling or warming of the liquid or substance by ambient conditions. When a temperature is used herein without specifying xe2x80x9cinletxe2x80x9d or xe2x80x9cconstant,xe2x80x9d the temperature may be considered as either an xe2x80x9cinletxe2x80x9d or xe2x80x9cconstantxe2x80x9d temperature.
In one embodiment, soaking in water, or any other suitable liquid, at about a constant 40xc2x0 C. for about 8 hours is sufficient. In another embodiment, soaking at about a constant 15xc2x0 C. for about 24 hours is sufficient. In yet another embodiment, soaking at about a constant 35xc2x0 C. for about 12 hours is sufficient. Accordingly, the soybeans may be soaked in a liquid at a constant temperature of about 40xc2x0 C. to about 15xc2x0 C. for about 8 to about 24 hours.
Alternatively, the soybeans may be soaked in an additional embodiment in water having an inlet temperature of about 40xc2x0 C. for about 12 hours; in another embodiment in water having an inlet temperature of about 35xc2x0 C. for about 15 hours, and yet another embodiment, in water having an inlet temperature of about 15xc2x0 C. for about 30 hours. Accordingly, the soybeans may be soaked in water having an inlet temperature of about 40xc2x0 C. to about 15xc2x0 C. for about 12 to about 30 hours. During this soaking step, the soybeans are re-hydrated to initiate activation of the endogenous enzymes in the soybeans. After sufficient soaking, the water is removed from the mixing vessel and the partially hydrated soybeans are rinsed in water at about 40xc2x0 C.
The soybeans are then incubated in a model xe2x80x9cLxe2x80x9d steam jacketed kettle (BAR, N.A. Inc., Seymour, Ill.) or other comparable steam kettle or incubator, to further activate the endogenous enzymes. In a first process, the soybeans are incubated to about 40xc2x0 C. for about 10 hours, and may be stirred at least once at the third hour. In another process, the soybeans are incubated at about a constant 35xc2x0 C. for about 12 hours with the soybeans being stirred, if desired, once at about the 6th hour. In a third process, the soybeans are incubated at about 20xc2x0 C. constant for about 60 hours and may be stirred, if desired, at about the 30th hour. Accordingly, the soybeans may be soaked at a constant temperature of about 40xc2x0 C. to about 20xc2x0 C. for about 10 hours to about 60 hours. The whole soybeans may be incubated at any temperature and duration of time as long as the soybeans are re-hydrated and the proteinases and carbohydrases of the soybean remain enzymatically active.
After incubation, the soybeans may be re-soaked in water in a kettle to re-soften the soybeans at about a constant 50xc2x0 C. for about one-half hour in a first embodiment; at about a constant 40xc2x0 C. for about one and a half hours in a second embodiment; and at about a constant 45xc2x0 C. for about one hour in a third embodiment. Accordingly, the soybeans may be re-soaked in water having a constant temperature of about 50xc2x0 C. to about 40xc2x0 C. for about one-half hour to about one and a half hours. After the re-soaking, the water is removed from the steam jacketed kettle, and the soybeans are rinsed with water to reduce the microbial load of the soybeans. In a first embodiment, this water may be at temperatures from about 15xc2x0 C. to about 50xc2x0 C. In a second embodiment, the water may be at about 50xc2x0 C.
Next, the soybeans may be dehulled, that is, their skins are removed from the cotyledons of the whole soybeans. Dehulling reduces the fibrous content of the beans, as the hulls are comprised primarily of fiber. A wet-type model BB soybean dehuller (BAR, N.A., Seymour, Ill.) or other comparable dehuller, may be used to dehull the whole soybeans. The dehuller separates the hulls from the cotyledons and the cotyledons are collected. Alternatively, the soybeans may be extracted using conventional physical or chemical processes as will be appreciated by those skilled in the art.
The cotyledons are replaced in the steam jacketed kettle for further incubation. During this step of the process, the soybean proteins are further hydrolyzed. For example, polypeptides, that is, peptide chains having more than ten amino acids, are hydrolyzed to shorter oligopeptides, that is, peptide chains having two to ten amino acids. The cotyledons, in one embodiment, may be incubated at about 45xc2x0 C. for about 6 hours, in a second embodiment, at about 40xc2x0 C. for about 8 hours, in a third embodiment, at about 30xc2x0 C. for about 10 hours, and in a fourth embodiment at about 25xc2x0 for about 12 hours. Accordingly, the cotyledons are incubated at about 45xc2x0 C. to about 25xc2x0 C. for about 6 hours to about 12 hours. Any temperature and duration of incubation is satisfactory as long as the proteinases in the cotyledons are activated to enzymatically assist in the further hydrolysis of soy proteins in the cotyledons. Additional proteinases or enzymes may be added to the cotyledons to enhance protein hydrolysis.
The protein hydrolyzed cotyledons are then boiled in water for about 25 to about 40 minutes in a first embodiment and about 30 minutes in a second embodiment, in the steam jacketed kettle to induce coagulation and gelatinization of partially hydrolyzed soybeans. xe2x80x9cGelatinizationxe2x80x9d refers to the formation of a gel or gel-like substance on heating a suspension of polysaccharides or mixtures of polysaccharides and proteins. After boiling, the steam may be turned off. In an alternative embodiment, the cotyledons may be boiled in a solution of food grade buffers, alkali solutions or other solutions as will be appreciated by those skilled in the art, at a temperature of about 65xc2x0 C. to about 150xc2x0 C., and a pH of about 6.2 to about 7.5. Examples of suitable food grade buffers are citrate and phosphate; examples of alkali solutions are those including sodium bicarbonate, sodium hydroxide, and/or potassium hydroxide.
The gelatinized cotyledons may be milled with a model 150 BMI stainless steel mill (BAR N.A. Inc., Seymour, Ill.) or other capable mill. xe2x80x9cMillingxe2x80x9d means physically breaking down the gelatinized cotyledons into a slurry of small particles.
The cotyledon slurry may be incubated to hydrolyze the carbohydrates, that is, the saccharides in the soybeans. For example, cellulose and hemicellulose (known as polysaccharides) are partially hydrolyzed to beta-glucans and sugars. To enhance the breakdown of the carbohydrates, enzyme(s) is/are added to the cotyledon slurry. Cellulase or a mixture of cellulases is the preferred enzyme, but any other enzyme capable of enhancing the carbohydrate hydrolysis may be used, as will be appreciated by those skilled in the art. In a first embodiment, about 0 to about 10 grams of cellulase per kilogram dry bean weight is added. In another embodiment, about 1 to about 3 grams of cellulase per kilogram dry bean weight is added to the slurry. The slurry is then mixed in one embodiment at a pH of about 6.0 to 7.0, in another embodiment of about 6.0, followed by incubation of the slurry and cellulase enzymes at about 35xc2x0 to about 55xc2x0 C. for about 3 hours to about 20 seconds, respectively. The cellulase activity in the slurry may be terminated at the end of incubation by heating the slurry in the kettle to about 90xc2x0 C. for about xc2xd hour, followed by cooling the slurry to about 60xc2x0 C. in the kettle.
The cooled slurry may be deodorized using conventional vacuum pan or evaporator deodorizing processes which will be appreciated by those skilled in the art. Once the slurry is deodorized and concentrated, it may be cooled to about 20xc2x0 C. This slurry, after the aforementioned processing, is referred to as the xe2x80x9chydrolyzed soybean base.xe2x80x9d In a first embodiment, the hydrolyzed soy base has a total solids content of about 5% to about 35%, in a second embodiment, about 10% to about 20%, and in a third embodiment, about 15%. The total solids content may vary according to the amount of water that bonds to the polysaccharides, or the variety of whole soybeans used in the process.
The hydrolyzed soybean base may then be mixed in a mixing tank at about room temperature with sweeteners, flavoring, stabilization aids and coloring as desired in a complete soy beverage. Examples of ingredients that may be added include sucrose, fructose, sea salt, xanthan gum, guar gum, lecithin, flavor, and coloring. After all the ingredients are mixed, the formulation may be stirred and stored at about xe2x88x9220xc2x0 C. to about 60xc2x0 C. in a first embodiment, at about 0xc2x0 to about 10xc2x0 C. in a second embodiment, and at about 4xc2x0 C. in a third embodiment.
The formulation may be homogenized. xe2x80x9cHomogenizationxe2x80x9d refers to a mechanical process for creating a colloidal system that is unaffected by gravity. In a first embodiment, the formulation may be homogenized from about 4,000 psi to about 30,000 psi. In a second embodiment, the formulation may be homogenized at about 15,000 psi in a Rannie 12.56 VH Homogenizer (APV Americas, Wilmington, Mass.), or other comparable homogenizer. It will be appreciated by those skilled in the art that the higher the pressure, the more smooth and consistent the formulation will become.
The homogenized formulation may be sterilized and aseptically packaged. xe2x80x9cSterilizationxe2x80x9d refers to destruction of all bacteria and other infectious organisms in the homogenized formulation or soy beverage. The homogenized formulation may be sterilized in an Armfield FT74DI direct steam injection apparatus, available from Armfield Limited of Hampshire, England, or other comparable sterilizer, at ultra-high temperatures as will be appreciated by those skilled in the art. In the preferred embodiment, the formulation is sterilized at temperature of about 150xc2x0 C. for about 1 to about 2 seconds in a first embodiment and at about 145xc2x0 C. for about 5 seconds in a second embodiment. Heat treating at ultra high temperatures for significantly longer periods of time tends to break down the flavoring and coloring of the homogenized formulation. The sterilized homogenized formulation, that is, the resultant soy beverage, may be aseptically packaged to prevent recontamination, in a first embodiment, by hermetic sealing. The sterilized homogenized formulation may be contained in any glass, plastic or other container that is capable of being hermetically sealed. The sterilized homogenized formulation may be stored at room temperature without risk of contamination by bacteria.
The homogenized formulation may alternatively be pasteurized. xe2x80x9cPasteurizingxe2x80x9d means killing or inactivating bacterial or other infectious organisms therein. The homogenized formulation may be ultra-pasteurized at about 75xc2x0 C. to about 99xc2x0 C. for about one-half hour to about one minute, respectively. The pasteurized homogenized formulation may be stored in any suitable container and then refrigerated.
The resultant soy beverage, that is, either the sterilized homogenized formulation or the pasteurized homogenized formulation, may be consumed in the same manner as known for existing beverages.